Cloud computing has become a widely adopted model for providing enterprises with access to large amounts of computing resources. One of the primary technologies underlying cloud computing is virtualization. Virtualization allows a single physical computing server to host multiple virtual machine instances each of which operates as an independent computing system with its own operating system. Virtual machine instances frequently provide a broad variety of computing services, e.g., a retail shopping website backed by virtual machine instances running web-servers, application servers, and database applications. In this way, cloud computing allows an enterprise to obtain a variety of computing resources as needed without having to invest and maintain an underlying physical computing infrastructure.
In addition to providing virtual machine instances, a cloud computing provider typically offers a variety of other computing resources to enterprise clients. For example, the service provider may offer database services, persistent storage, private networking services for VM instances, load balancing, auto scaling, cloud formation, etc., as part of a cloud based services offering. Cloud providers typically offer such computing resources using web services. Generally, a web service provides an application made available over the internet which communicates with endpoints and other services using standardized messaging protocols. For example, an enterprise customer may invoke API calls exposed by the service provider to launch, configure, access, and manage cloud based computing resources as needed (e.g., by composing applications which invoke API calls or using a service console or command line tool which invokes such API calls).
While virtual machine instances are frequently referred to as existing “in the cloud,” many providers offer cloud based computing resources for defined regions. For example, a cloud based provider may allow users to launch computing resources in specific regions. Such regions may be geographically based (e.g., Western United States and Eastern United States) as well as based on political boundaries (e.g., North America U.S. versus North America Canada).